It is often explained in textbooks that the synthetic expression method (synthesis ofnotation by auxiliary tables or other parts of the schedule) of the Dewey Decimal Classification(DDC) is a device for treating complex subjects. However, such an explanation is wrong andbased upon a confusion of the "synthetic expression method" for notation system with the"analytico-synthetic procedure" for subject structure. The analytico-synthetic procedure is aprocedure for applying division principles to subjects specific to classification systems withmulti-dimensional structure such as Colon Classification. While division principles are to beapplied in due order in the hierarchical structure, they can freely be applied in the multidimensional structure. Therefore, complex subjects can easily be classified and thus bettertreated in the latter structure. Also, it is true that most classification systems with the multidimensional structure have adopted the synthetic expression method for their notation systems. However, the subject structure is in principle nothing to do with the notation system ofa classification system. Any subject, which can be expressed by the synthetic expressionmethod, can also be expressed by the enumerative method. Therefore, the synthetic expressionmethod of the DDC cannot be an effective device for treating complex subjects (as comparedwith the enumerative expression method).